(a) Field of the Invention
The present invention relates to a plasma display panel (PDP) and a method for manufacturing the same.
(b) Description of the Related Art
A PDP is a display device that displays images through excitation of phosphors by plasma discharge. Vacuum ultraviolet (VUV) rays emitted from plasma obtained via gas discharge excite phosphor layers, which then emit visible red (R), green (G), and blue (B) light to thereby form images. The PDP has many advantages including an ability to be made having large screen sizes of 60 inches and greater, a thin profile of 10 cm or less, a wide viewing angle and good color reproduction due to the self-emissive nature of the PDP (similar to a cathode-ray tube), and high productivity and low manufacturing costs as a result of manufacturing processes that are more simple than those involved with liquid crystal displays. As a result, the PDP is experiencing increasingly widespread use in homes and industries.
In a conventional alternating current (AC) PDP, a rear substrate and a front substrate are provided opposing one another with a predetermined gap therebetween. Formed on a surface of the rear substrate opposing the front substrate are a plurality of address electrodes. The address electrodes are formed in a stripe pattern along a first direction. A first dielectric layer is formed on the rear substrate covering the address electrodes, and a plurality of barrier ribs are formed on the first dielectric layer. The barrier ribs are formed either in a stripe pattern along the first direction and at areas between the address electrodes, or in a matrix pattern along the first direction as well as a second direction that is perpendicular to the first direction. Red, green, and blue phosphor layers are respectively formed between adjacent pairs of the barrier ribs.
Formed on a surface of the front substrate opposing the rear substrate are a plurality of display electrodes (sustain and scan electrodes), each comprised of a pair of transparent electrodes and a corresponding pair of bus electrodes. A second dielectric layer and a magnesium oxide (MgO) protection layer are formed (in this order) on the front substrate covering the display electrodes.
Each area between one of the address electrodes and a pair of the display electrodes, and delimited by the intersection (or crossing) of these elements, forms a discharge cell. Several millions of discharge cells can be formed in a matrix configuration by this arrangement. A memory characteristic is utilized to simultaneously drive the millions of discharge cells of the AC PDP.
In more detail, to realize discharge between an X electrode (sustain electrode) and a Y electrode (scan electrode) included in each pair of the display electrodes, a potential difference of a predetermined voltage is required. This potential difference is referred to as a firing voltage Vf. That is, in driving the AC PDP, if an address voltage Va is applied between one of the Y electrodes and one of the address electrodes, address discharge is initiated such that plasma is created in a corresponding discharge cell. Electrons and ions in the plasma migrate toward the electrodes of opposite polarity to thereby realize the flow of current.
However, because the first dielectric layer is formed over the address electrodes, and the second dielectric layer is formed over the display electrodes, most of the migrated space charges accumulate on the first and second dielectric layers, which are opposite in polarity. As a result, a net space potential between the Y electrodes and the address electrodes becomes less than the originally applied address voltage Va to weaken discharge and thereby terminate address discharge.
When the address discharge is terminated, a relatively small number of electrons accumulate toward the X electrodes, while a relatively large number of ions accumulate toward the Y electrodes. The charge accumulated on the second dielectric layer, which covers the X and Y electrodes, is referred to as a wall charge Qw, while the space voltage formed between the X and Y electrodes by the wall charge Qw is referred to as a wall voltage Vw.
Subsequently, if a predetermined discharge sustain voltage Vs is applied between the X electrodes and the Y electrodes, and if a sum of the discharge sustain voltage Vs and the wall voltage Vw (Vs+Vw) becomes larger than the firing voltage Vf, discharge is effected in the corresponding discharge cells. VUV rays generated as a result excite the corresponding phosphor layer such that visible light is emitted through the transparent front substrate.
Alternatively, when there is no address discharge applied between the Y electrodes and the address electrodes (i.e., when there is no application of an address voltage Va), no wall charge is present between the X and Y electrodes, and, ultimately, no wall voltage between the same. Hence, only the discharge sustain voltage Vs that is applied between the X and Y electrodes is formed in the discharge cell, and since this voltage alone is smaller than the firing voltage Vf, no discharge occurs in the gaseous spaces of the X and Y electrodes.
In the PDP operating as described above, many steps are involved between power input and obtaining the display of visible light. Further, the efficiency of converting energy in each of these steps is low. In fact, a conventional CRT has a better overall efficiency (brightness to power consumption ratio) than does a conventional PDP. The low energy efficiency of conventional PDPs is a serious drawback for the PDPs.